Tip: The password file must be read-only and not be accessible to any other user! Remove access rights to this file for all other users under Windows.

Connection settings

Defining a monitor to a Tomcat server requires the name or IP address of the machine to be monitored, as well as the connection port (the default port is 9004). In addition to these settings, a valid user account must be provided if authentication is enabled.

VM. JVM counters. Since Tomcat 5.5/6.0 is launched in a 1.5 VM, the following VM counters are provided:

Memory. The Java virtual machine has a heap that is the runtime data area from which memory for all class instances and arrays are allocated. It is created at the Java virtual machine start-up. Heap memory for objects is reclaimed by an automatic memory management system which is known as a garbage collector. The heap may be of a fixed size or may be expanded and shrunk.

Used. Represents the amount of memory currently used (in bytes).

% Used. Represents the percentage amount of memory currently used.

Committed. Represents the amount of memory (in bytes) that is guaranteed to be available for use by the Java virtual machine. The amount of committed memory may change over time (increase or decrease). The Java virtual machine may release memory to the system and committed could be less than init. committed will always be greater than or equal to used.

Max. Represents the maximum amount of memory (in bytes) that can be used for memory management. Its value may be undefined. The maximum amount of memory may change over time if defined. The amount of used and committed memory will always be less than or equal to max if max is defined. A memory allocation may fail if it attempts to increase the used memory such that used > committed even if used <= max would still be true (for example, when the system is low on virtual memory).

Garbage Collector. Garbage collection is the process that the Java virtual machine uses to find and reclaim unreachable objects to free up memory space. The Sun JVM defines garbage collection in two modes: Minor 'copy' and major 'MarkSweepCompact', .A minor collection runs relatively quickly and involves moving live data around the heap in the presence of running threads. A major collection is a much more intrusive garbage collection that suspends all execution threads while it completes its task. The following counters are available for both modes:

CollectionCount. Returns the number of collections that have occurred since last call.

CollectionTime. Returns the approximate accumulated collection elapsed time in milliseconds since last call.

Threads. Information on the thread system of the Java virtual machine.

ThreadCount. Returns the current number of live threads including both daemon and non-daemon threads.

DaemonThreadCount. Returns the current number of live daemon threads.

PeakThreadCount. Returns the peak live thread count since the Java virtual machine started or peak was reset.